Cube  Diff

// physics.cpp: no physics books were hurt nor consulted in the construction of
// this code. All physics computations and constants were invented on the fly
// and simply tweaked until they "felt right", and have no basis in reality.
// Collision detection is simplistic but very robust (uses discrete steps at
// fixed fps).

#include "cube.h"

#import "DynamicEntity.h"
#import "Entity.h"
#import "MapModelInfo.h"

// collide with player or monster
static bool
plcollide(
    DynamicEntity *d, DynamicEntity *o, float *headspace, float *hi, float *lo)
{
	if (o.state != CS_ALIVE)
		return true;
	const float r = o.radius + d.radius;
	if (fabs(o.o.x - d.o.x) < r && fabs(o.o.y - d.o.y) < r) {
		if (d.o.z - d.eyeheight < o.o.z - o.eyeheight) {
			if (o.o.z - o.eyeheight < *hi)
				*hi = o.o.z - o.eyeheight - 1;
		} else if (o.o.z + o.aboveeye > *lo)
			*lo = o.o.z + o.aboveeye + 1;

		if (fabs(o.o.z - d.o.z) < o.aboveeye + d.eyeheight)
			return false;
		if (d.monsterstate)
			return false; // hack
		*headspace = d.o.z - o.o.z - o.aboveeye - d.eyeheight;
		if (*headspace < 0)
			*headspace = 10;
	}
	return true;
}

// recursively collide with a mipmapped corner cube
static bool
cornertest(int mip, int x, int y, int dx, int dy, int *bx, int *by, int *bs)

{
	struct sqr *w = wmip[mip];
	int sz = ssize >> mip;
	bool stest =
	    SOLID(SWS(w, x + dx, y, sz)) && SOLID(SWS(w, x, y + dy, sz));
	mip++;
	x /= 2;
	y /= 2;
	if (SWS(wmip[mip], x, y, ssize >> mip)->type == CORNER) {
		*bx = x << mip;
		*by = y << mip;
		*bs = 1 << mip;
		return cornertest(mip, x, y, dx, dy, bx, by, bs);
	}
	return stest;
}

// collide with a mapmodel
static void
mmcollide(DynamicEntity *d, float *hi, float *lo)
{
	for (Entity *e in ents) {
		if (e.type != MAPMODEL)
			continue;

		MapModelInfo *mmi = getmminfo(e.attr2);
		if (mmi == nil || !mmi.h)
			continue;

		const float r = mmi.rad + d.radius;
		if (fabs(e.x - d.o.x) < r && fabs(e.y - d.o.y) < r) {
			float mmz =
			    (float)(S(e.x, e.y)->floor + mmi.zoff + e.attr3);

			if (d.o.z - d.eyeheight < mmz) {
				if (mmz < *hi)
					*hi = mmz;
			} else if (mmz + mmi.h > *lo)
				*lo = mmz + mmi.h;
		}
	}
}

// all collision happens here
// spawn is a dirty side effect used in spawning
// drop & rise are supplied by the physics below to indicate gravity/push for

	    : -1000.0f;

	for (int x = x1; x <= x2; x++)
		for (int y = y1; y <= y2; y++) {
			// collide with map
			if (OUTBORD(x, y))
				return false;
			struct sqr *s = S(x, y);
			float ceil = s->ceil;
			float floor = s->floor;
			switch (s->type) {
			case SOLID:
				return false;

			case CORNER: {
				int bx = x, by = y, bs = 1;
				if (x == x1 && y == y1 &&
				        cornertest(
				            0, x, y, -1, -1, &bx, &by, &bs) &&
				        fx1 - bx + fy1 - by <= bs ||
				    x == x2 && y == y1 &&
				        cornertest(
				            0, x, y, 1, -1, &bx, &by, &bs) &&
				        fx2 - bx >= fy1 - by ||
				    x == x1 && y == y2 &&
				        cornertest(
				            0, x, y, -1, 1, &bx, &by, &bs) &&
				        fx1 - bx <= fy2 - by ||
				    x == x2 && y == y2 &&
				        cornertest(
				            0, x, y, 1, 1, &bx, &by, &bs) &&
				        fx2 - bx + fy2 - by >= bs)
					return false;
				break;
			}

			case FHF: // FIXME: too simplistic collision with
			          // slopes, makes it feels like tiny stairs

	if (hi - lo < d.eyeheight + d.aboveeye)
		return false;

	float headspace = 10;
	for (id player in players) {
		if (player == [OFNull null] || player == d)
			continue;
		if (!plcollide(d, player, &headspace, &hi, &lo))
			return false;
	}
	if (d != player1)
		if (!plcollide(d, player1, &headspace, &hi, &lo))
			return false;
	// this loop can be a performance bottleneck with many monster on a slow
	// cpu, should replace with a blockmap but seems mostly fast enough
	for (DynamicEntity *monster in getmonsters())
		if (!vreject(d.o, monster.o, 7.0f) && d != monster &&
		    !plcollide(d, monster, &headspace, &hi, &lo))
			return false;
	headspace -= 0.01f;

	mmcollide(d, &hi, &lo); // collide with map models

	if (spawn) {
		// just drop to floor (sideeffect)
		d.o = OFMakeVector3D(d.o.x, d.o.y, lo + d.eyeheight);
		d.onfloor = true;
	} else {
		const float space = d.o.z - d.eyeheight - lo;

	}
}

// main physics routine, moves a player/monster for a curtime step
// moveres indicated the physics precision (which is lower for monsters and
// multiplayer prediction) local is false for multiplayer prediction

static void
moveplayer4(DynamicEntity *pl, int moveres, bool local, int curtime)
{
	const bool water = hdr.waterlevel > pl.o.z - 0.5f;
	const bool floating = (editmode && local) || pl.state == CS_EDITING;

	OFVector3D d; // vector of direction we ideally want to move in

	d.x = (float)(pl.move * cos(rad(pl.yaw - 90)));

	// detect wether player is outside map, used for skipping zbuffer clear
	// mostly

	if (pl.o.x < 0 || pl.o.x >= ssize || pl.o.y < 0 || pl.o.y > ssize)
		pl.outsidemap = true;
	else {
		struct sqr *s = S((int)pl.o.x, (int)pl.o.y);
		pl.outsidemap = SOLID(s) ||
		    pl.o.z < s->floor - (s->type == FHF ? s->vdelta / 4 : 0) ||
		    pl.o.z > s->ceil + (s->type == CHF ? s->vdelta / 4 : 0);
	}

	// automatically apply smooth roll when strafing

	}
	pl.inwater = water;
}

void
moveplayer(DynamicEntity *pl, int moveres, bool local)
{
	loopi(physicsrepeat) moveplayer4(pl, moveres, local,
	    i ? curtime / physicsrepeat
	      : curtime - curtime / physicsrepeat * (physicsrepeat - 1));
}